Dynamic optimization of multipass turning of a flexible workpiece considering the effect of cutting sequence

In multipass turning of flexible workpieces, the selection of the sequence of cutting passes is as important as the selection of machining parameters (depth of cut, feed rate, and cutting speed). This is because the varying workpiece diameter has an effect on the optimization objective function and constraints. In general, there should be a total of five decision variables in multipass turning optimization problems, that is, the three fundamental machining parameters, the number of cutting passes, and the sequence of cutting passes. However, this issue has been paid little attention in literature. This study presents an effective method for optimizing the cutting sequence and the machining parameters to suppress the deformation and chatter during turning a flexible cantilever tube. The mathematical optimization model distinct from the simplified model used in many previous studies is formulated, where the deformation and chatter constraints are intensively deduced from the dynamic analysis. The optimization problem is solved in two phases. The first phase is to determine the minimum production time for each cutting pass for the predefined depths of cut. A particle swarm optimization is employed to accomplish this step. After that, a dynamic programming technique is adopted to achieve the optimal sequential subdivision of the total depth of cut. A computational experiment elaborates the methodology. The results demonstrate that the proposed method is of generality and more efficient in comparison with other algorithms.